The Lean Computer Science Library (CSLib)
CSLib is the Lean Computer Science Library, a formalisation of computer science theories and tools in Lean 4 that provides APIs for formal verification, certified software, and connecting different CS developments. Built with Lean 4 and Lake as its build system, it depends primarily on Mathlib. The library covers multiple problem domains including computability theory and automata, programming language formalisations (such as the Lambda Calculus and Calculus of Communicating Systems), logic formalisations (including Linear Logic and Hennessy-Milner Logic), cryptography, and distributed systems, with particular emphasis on semantics as a unifying foundation across these areas.